1. Field of the Invention
The invention relates to a laryngeal mask airway device with drug delivery means. More specifically, the invention relates to a paediatric laryngeal mask airway device with a liquid drug delivery means.
2. Description of Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98
The laryngeal mask airway device is a well-known device that is useful for establishing airways in unconscious patients. U.S. Pat. No. 4,509,514 is one of the many publications that describe laryngeal mask airway devices. Such devices have been in use for many years and offer an alternative to the older, even better known, endotracheal tube. For at least seventy years, endotracheal tubes comprising a long slender tube with an inflatable balloon disposed at the tube's distal end have been used for establishing airways in unconscious patients. In operation, the endotracheal tube's distal end is inserted through the mouth of the patient, past the patient's laryngeal inlet (or glottic opening), and into the patient's trachea. Once so positioned, the balloon is inflated so as to form a seal with the interior lining of the trachea. After this seal is established, positive pressure may be applied to the tube's proximal end to ventilate the patient's lungs. Also, the seal between the balloon and the inner lining of the trachea protects the lungs from aspiration (e.g., the seal prevents material regurgitated from the stomach from being aspirated into the patient's lungs).
Although they have been enormously successful, endotracheal tubes suffer from several major disadvantages. The principal disadvantage of the endotracheal tube relates to the difficulty of properly inserting the tube. Inserting an endotracheal tube into a patient is a procedure that requires a high degree of skill, even more so when the patient is a child or and infant. Also, even for skilled practitioners, insertion of an endotracheal tube is sometimes difficult or not possible. Also, inserting an endotracheal tube normally requires manipulations of the patient's head and neck and further requires the patient's jaw to be forcibly opened widely. These necessary manipulations make it difficult, or undesirable, to insert an endotracheal tube into a patient who may be suffering from a neck injury.
In contrast to the endotracheal tube, it is relatively easy to insert a laryngeal mask airway device into a patient and thereby establish an airway. Also, the laryngeal mask airway device is a “forgiving” device in that even if it is inserted improperly, it still tends to establish an airway. Also, the laryngeal mask airway device may be inserted with only relatively minor manipulations of the patient's head, neck, and jaw. Further, the laryngeal mask airway device provides for ventilation of the patient's lungs without requiring contact with the sensitive inner lining of the trachea and the size of the airway established is typically significantly larger than the size of the airway established with an endotracheal tube. Also, the laryngeal mask airway device does not interfere with coughing to the same extent as endotracheal tubes. Largely due to these advantages, the laryngeal mask airway device has enjoyed increasing popularity in recent years.
In the case of respiratory diseases, it is sometimes necessary to deliver drug directly into the lungs. Respiratory Distress Syndrome (RDS) is an example of such a disease, in which the patient has a deficiency in pulmonary surfactant. Pulmonary surfactant is a substance naturally found in the lungs, which reduces alveolar collapse by decreasing surface tension in the alveoli. This condition affects more particularly newborns and is a major cause of mortality in premature infants. It has been observed that the more premature the infant, the less pulmonary surfactant production because of lung immaturity and the higher the probability for RDS.
Respiratory failure may be avoided by administrating an exogeneous surfactant, which may be naturally or synthetically obtained, directly into the pulmonary system. This can for example be achieved by intubating the trachea but this method presents obvious disadvantages for the patient.
Attempts have been made to inject exogeneous surfactant through an endotracheal tube. However, due to the difficulty of properly inserting and positioning the tube, the substance is not properly administered to the lungs. It has to be pointed out that a major issue with this treatment is its considerable expense and any loss of exogeneous surfactant by improper administration should be avoided. Improper administration of exogeneous surfactant may also be harmful to the patient, in particular when the patient is a premature infant. Indeed, if the surfactant is splashed against the vocal cords, it might trigger a laryngeal spasm, which is likely to provoke the cords into closing. There is therefore the need for a device, which delivers liquid drugs, such as exogeneous surfactant, safely and efficiently to the pulmonary system, with minimum loss of drug.